The present invention relates generally to brake systems for automotive vehicles, and more particularly, to an autonomous emergency braking system.
Automotive brake systems are the result of a long evolutionary process and are one of the most important systems in a vehicle. Typical brake systems include a master cylinder, located under the hood, which is directly connected to a brake pedal. The master cylinder converts mechanical pressure applied to the brake pedal into a proportional amount of hydraulic pressure. This hydraulic pressure is used to actuate the vehicle brakes. Many brake systems also use the engine""s energy to add pressure to the master cylinder.
To improve upon standard braking systems, various automatic braking systems have been suggested in the prior art. U.S. Pat. No. 5,699,040 discloses a vehicle collision preventing system. The ""040 patent uses a distance measuring unit to determine how close a host vehicle is to an object in front of it. Once the distance between the host vehicle and the subject vehicle becomes too small, an automatic braking signal is generated by a judging means.
U.S. Pat. No. 6,084,508 discloses an automatic emergency braking method and arrangement. Through the use of a radar or laser sensor, the ""508 patent monitors the surroundings, including changes in the remote vehicle""s actions. Based on changes in the surroundings automatic braking is done with maximum braking pressure.
Unfortunately, the systems suggested by these patents have several disadvantages. In many situations, application of maximum braking pressure may have a detrimental effect. Likewise, application of brake force without consideration of the presence or belted status of occupants is not desirable. Additionally, the driver should have the ability to override any automatic braking feature in the case of a system fault. Finally, reducing engine speed before automatic application of brakes may improve overall system performance.
The disadvantages associated with these conventional automatic emergency braking techniques have made it apparent that a new technique for automatic emergency braking is needed. The new technique should reduce overall vehicle kinetic energy while enhancing driver performance. The present invention is directed to these ends.
It is, therefore, an object of the invention to provide an improved and reliable autonomous emergency braking system.
In accordance with the objects of this invention, an autonomous emergency braking system is provided. The autonomous emergency braking system includes an accelerator pedal operated by the driver coupled to a braking system and used to control the overall vehicle speed. When a forward detection apparatus detects an imminent contact, the braking system automatically applies braking force to the vehicle while the vehicle engine speed is reduced. The amount of brake force applied is a continuous function of relative speed, relative distance, collision probability and target classification. The braking force may be reduced when the driver or passenger are unbuckled or may be disabled if the driver applies full throttle.
The present invention thus achieves an improved emergency brake assist system. The present invention is advantageous in that it enhances driver braking performance during imminent contact situations. Additionally, the present invention may maintain standard braking levels when an occupant is unbelted.